Raman optical fiber sensing device for pipeline leakage chaos time-frequency comb correlation detection

Abstract

The invention relates to the technical field of distributed optical fiber sensing, and discloses a Raman optical fiber sensing device for pipeline leakage chaos time frequency comb correlation detection, which comprises an FP semiconductor laser, the output end of the FP semiconductor laser is connected with a polarization controller, the polarization controller is connected with a first port of a first optical coupler, and the first optical coupler is connected with a second port of a second optical coupler. A second port of the first optical coupler is connected with a second port of the circulator through the optical attenuator, a first port of the circulator is connected with the tunable Bragg grating, and a third port of the circulator is connected with a third port of the second optical coupler; a first port of the second optical coupler is connected with a third port of the first optical coupler through the erbium-doped optical fiber amplifier, a second port of the second optical coupler is connected with an input end of the semiconductor optical modulator, and the semiconductor optical modulator is connected with the pulse comb generator. The output end of the semiconductor optical modulator is connected with the input end of a third optical coupler, the first output end of the third optical coupler is connected with the input end of a first photoelectric detector, and the output end of the first photoelectric detector is connected with a computer through an acquisition card.

Description

Technical Field

[0001] The invention relates to the technical field of distributed optical fiber sensing, in particular to a Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage. Background Art

[0002] In the field of pipeline transportation, pipelines are the main channels for transporting energy and chemicals such as oil and natural gas. Once a leak occurs, it will not only cause huge economic losses, but may also lead to serious environmental pollution and safety accidents. The importance of pipeline leak detection is self-evident.

[0003] In recent years, distributed optical fiber sensing technology has been widely used in the field of pipeline leakage detection due to its advantages of distribution, electrical insulation, corrosion resistance, and electromagnetic resistance. By laying sensing optical fibers around the pipeline, changes in the temperature and strain of the pipeline can be monitored in real time, thereby quickly discovering and locating the leakage point.

[0004] However, the current Raman distributed fiber optic sensing technology has the following limitations: First, in the existing technology, the distributed optical fiber sensing technology based on Raman scattering is limited by the pulse width, and its spatial resolution is low and difficult to exceed 1 m; 2. In the existing technology, the detection method of Raman distributed optical fiber sensing technology has a technical bottleneck of low signal-to-noise ratio. Its sensing distance is short and the spatial resolution is limited, which cannot exceed 100 km and cannot meet the requirements.

[0005] In order to solve the above problems, the present invention proposes a Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage. Summary of the invention

[0006] In order to solve the technical problems that the current Raman distributed optical fiber sensing technology is limited by pulse width, has low spatial resolution, is trapped by the technical bottleneck of low signal-to-noise ratio, and cannot break through the transmission distance, the present invention provides a Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage.

[0007] The present invention is implemented by the following technical solutions: The Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage comprises an FP semiconductor laser, wherein the output end of the FP semiconductor laser is connected to a polarization controller, the polarization controller is connected to a first port of a first optical coupler, the second port of the first optical coupler is connected to a second port of a circulator via an optical attenuator, the first port of the circulator is connected to a tunable Bragg grating, and the third port of the circulator is connected to a third port of a second optical coupler; the first port of the second optical coupler is connected to the third port of the first optical coupler via an erbium-doped optical fiber amplifier, the second port of the second optical coupler is connected to an input end of a semiconductor optical modulator, the semiconductor optical modulator is connected to a pulse comb generator, the output end of the semiconductor optical modulator is connected to an input end of a third optical coupler, the first output end of the third optical coupler is connected to an input end of a first photodetector, and the output end of the first photodetector is connected to a computer via an acquisition card.

[0008] During implementation, the Raman fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage designed by the present invention comprises an FP semiconductor laser outputting laser light, the output end of the FP semiconductor laser is connected to a polarization controller, the polarization controller is connected to a first port of a first optical coupler, the second port of the first optical coupler is connected to a second port of a circulator through an optical attenuator, the first port of the circulator is connected to a tunable Bragg grating, so that the laser light is reflected after input, the reflected laser light enters from the first port of the circulator, and is output from a third port of the circulator, the third port of the circulator is connected to a third port of the second optical coupler; the first port of the second optical coupler is connected to the third port of the first optical coupler through an erbium-doped fiber amplifier, and an optical signal is fed back, thereby modulating a high-dimensional tunable chaotic laser light; the second port of the second optical coupler is connected to an input end of a semiconductor optical modulator, the semiconductor optical modulator is connected to a pulse comb generator, the output end of the semiconductor optical modulator is connected to an input end of a third optical coupler, the first output end of the third optical coupler is connected to an input end of a first photodetector, and the output end of the first photodetector is connected to a computer through an acquisition card.

[0009] Furthermore, the second output end of the third optical coupler is connected to the input end of the pulsed erbium-doped fiber amplifier, the output end of the pulsed erbium-doped fiber amplifier is connected to the input end of the first wavelength division multiplexer, the output end of the first wavelength division multiplexer is connected to the input end of the first high-sensitivity optical amplifier via the first optical switch, the output end of the first high-sensitivity optical amplifier is connected to the input end of the second photodetector, and the output end of the second photodetector is connected to the computer via the acquisition card.

[0010] Furthermore, the bypass port of the first wavelength division multiplexer is connected to the input end of the second wavelength division multiplexer through a sensing optical fiber, the output end of the second wavelength division multiplexer is connected to the input end of a second high-sensitivity optical amplifier through a second optical switch, the output end of the second high-sensitivity optical amplifier is connected to the input end of a third photodetector, and the output end of the third photodetector is connected to a computer through an acquisition card.

[0011] Furthermore, the computer demodulates the distributed temperature information along the sensing optical fiber according to the collected detection information of the first photodetector, the second photodetector and the third photodetector.

[0012] Compared with the prior art, the present invention has the following beneficial effects: the present invention is based on the fact that high-dimensional tunable chaotic lasers at different wavelengths and in different combing states can excite Raman anti-Stokes nonlinear bidirectional scattering signals in different chaotic states. By introducing technologies such as high-dimensional tunable chaotic lasers and chaos correlation analysis, the present invention makes important contributions to pipeline safe operation and environmental protection, brings significant economic and social benefits to related industries, and makes important contributions to pipeline safe operation and environmental protection.

[0013] Compared with the traditional single-feedback chaotic laser signal, the chaotic laser time-frequency comb sequence can increase the light flux coupled into the sensing fiber by using the high coupling light flux and "pointer" positioning capability of the pulse comb, thereby effectively increasing the sensing distance. In addition, this project can improve the sensing spatial resolution to the centimeter level based on the picosecond narrowband correlation peak of the high-dimensional tunable chaotic laser in principle, which can break through the limitation of the spatial resolution of the traditional Raman scattering distributed optical fiber sensing technology by the pulse light time domain reflection positioning principle and the pulse width of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram showing the structure of the present invention.

[0015] In the figure: 1-FP semiconductor laser, 2-polarization controller, 3-first optical coupler, 3a-first port of the first optical coupler, 3b-second port of the first optical coupler, 3c-third port of the first optical coupler, 4-optical attenuator, 5-circulator, 5a-first port of the circulator, 5b-second port of the circulator, 5c-third port of the circulator, 6-tunable Bragg grating, 7-erbium-doped fiber amplifier, 8-second optical coupler, 8a-first port of the second optical coupler, 8b-second port of the second optical coupler, 8c-third port of the second optical coupler, 9-semiconductor optical modulator , 10-pulse comb generator, 11-third optical coupler, 12-pulse erbium-doped fiber amplifier, 13-sensing fiber, 14-first wavelength division multiplexer, 14a-input end of the first wavelength division multiplexer, 14b-output end of the first wavelength division multiplexer, 14c-bypass port of the first wavelength division multiplexer, 15-second wavelength division multiplexer, 16-first optical switch, 17-second optical switch, 18-first high-sensitivity optical amplifier, 19-second high-sensitivity optical amplifier, 20-first photodetector, 21-second photodetector, 22-third photodetector, 23-acquisition card, 24-computer. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0017] The Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage comprises an FP semiconductor laser 1 outputting laser light, the output end of the FP semiconductor laser 1 is connected to a polarization controller 2, the polarization controller 2 is connected to a first port 3a of a first optical coupler 3, the second port 3b of the first optical coupler 3 is connected to a second port 5b of a circulator 5 through an optical attenuator 4, the first port 5a of the circulator 5 is connected to a tunable Bragg grating 6, so that the laser light is reflected after input, the reflected laser light enters from the first port 5a of the circulator 5, and is output from a third port 5c of the circulator 5, the third port 5c of the circulator 5 is connected to the second optical coupler 3a, and the second optical coupler 3a is connected to the second port 5b of the circulator 5 through an optical attenuator 4, the first port 5a of the circulator 5 is connected to a tunable Bragg grating 6, and the laser light is reflected after input, the reflected laser light enters from the first port 5a of the circulator 5, and is output from the third port 5c of the circulator 5, and the third port 5c of the circulator 5 is connected to the second optical coupler 3a. 8 is connected to the third port 8c of the optical coupler 8; the first port 8a of the second optical coupler 8 is connected to the third port 3c of the first optical coupler 3 through the erbium-doped fiber amplifier 7, and the optical signal is fed back to modulate the high-dimensional tuned chaotic laser; the second port 8b of the second optical coupler 8 is connected to the input end of the semiconductor optical modulator 9, the semiconductor optical modulator 9 is connected to the pulse comb generator 10, the output end of the semiconductor optical modulator 9 is connected to the input end of the third optical coupler 11, the first output end of the third optical coupler 11 is connected to the input end of the first photodetector 20, and the output end of the first photodetector 20 is connected to the computer 24 via the acquisition card 23.

[0018] Preferably, the second output end of the third optical coupler 11 is connected to the input end of the pulsed erbium-doped fiber amplifier 12, the output end of the pulsed erbium-doped fiber amplifier 12 is connected to the input end 14a of the first wavelength division multiplexer 14, the output end 14b of the first wavelength division multiplexer 14 is connected to the input end of the first high-sensitivity optical amplifier 18 via the first optical switch 16, the output end of the first high-sensitivity optical amplifier 18 is connected to the input end of the second photodetector 21, and the output end of the second photodetector 21 is connected to the computer 24 via the acquisition card 23.

[0019] Preferably, the bypass port 14c of the first wavelength division multiplexer 14 is connected to the input end of the second wavelength division multiplexer 15 through the sensing optical fiber 13, the output end of the second wavelength division multiplexer 15 is connected to the input end of the second high-sensitivity optical amplifier 19 via the second optical switch 17, the output end of the second high-sensitivity optical amplifier 19 is connected to the input end of the third photodetector 22, and the output end of the third photodetector 22 is connected to the computer 24 via the acquisition card 23.

[0020] Preferably, the computer 24 demodulates the distributed temperature information along the sensing optical fiber according to the collected detection information of the first photodetector 20 , the second photodetector 21 and the third photodetector 22 .

[0021] The scope of protection claimed by the present invention is not limited to the above specific embodiments. For those skilled in the art, the present invention may have various deformations and changes. Any modifications, improvements and equivalent substitutions made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage, characterized by: The invention comprises an FP semiconductor laser (1), wherein the output end of the FP semiconductor laser (1) is connected to a polarization controller (2), the polarization controller (2) is connected to a first port (3a) of a first optical coupler (3), the second port (3b) of the first optical coupler (3) is connected to a second port (5b) of a circulator (5) via an optical attenuator (4), the first port (5a) of the circulator (5) is connected to a tunable Bragg grating (6), the third port (5c) of the circulator (5) is connected to a third port (8c) of a second optical coupler (8); and the first port (5b) of the second optical coupler (8) is connected to a third port (8c) of the second optical coupler (8). (8a) is connected to the third port (3c) of the first optical coupler (3) through an erbium-doped fiber amplifier (7), the second port (8b) of the second optical coupler (8) is connected to the input end of a semiconductor optical modulator (9), the semiconductor optical modulator (9) is connected to a pulse comb generator (10), the output end of the semiconductor optical modulator (9) is connected to the input end of a third optical coupler (11), the first output end of the third optical coupler (11) is connected to the input end of a first photodetector (20), and the output end of the first photodetector (20) is connected to a computer (24) via an acquisition card (23).

2. The Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage according to claim 1 is characterized in that: The second output end of the third optical coupler (11) is connected to the input end of the pulsed erbium-doped fiber amplifier (12), the output end of the pulsed erbium-doped fiber amplifier (12) is connected to the input end (14a) of the first wavelength division multiplexer (14), the output end (14b) of the first wavelength division multiplexer (14) is connected to the input end of the first high-sensitivity optical amplifier (18) via the first optical switch (16), the output end of the first high-sensitivity optical amplifier (18) is connected to the input end of the second photodetector (21), and the output end of the second photodetector (21) is connected to the computer (24) via the acquisition card (23).

3. The Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage according to claim 1 is characterized in that: The bypass port (14c) of the first wavelength division multiplexer (14) is connected to the input end of the second wavelength division multiplexer (15) via a sensing optical fiber (13); the output end of the second wavelength division multiplexer (15) is connected to the input end of a second high-sensitivity optical amplifier (19) via a second optical switch (17); the output end of the second high-sensitivity optical amplifier (19) is connected to the input end of a third photodetector (22); and the output end of the third photodetector (22) is connected to a computer (24) via an acquisition card (23).

4. The Raman optical fiber sensing device for chaotic time-frequency comb correlation detection of pipeline leakage according to claim 1 is characterized in that: The computer (24) demodulates distributed temperature information along the sensing optical fiber based on the collected detection information of the first photoelectric detector (20), the second photoelectric detector (21) and the third photoelectric detector (22).

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